Ann Clin Neurophysiol.  2017 Jul;19(2):118-124. 10.14253/acn.2017.19.2.118.

Electroencephalography for the diagnosis of brain death

• Lee SY
• Kim WJ
• Kim JM
• Kim J
• Park S
• The Korean Society of Clinical Neurophysiology Education Committee

• KMID: 2387232
• DOI: http://doi.org/10.14253/acn.2017.19.2.118

Abstract

Electroencephalography (EEG) is frequently used to assist the diagnosis of brain death. However, to date there have been no guidelines in terms of EEG criteria for determining brain death in Korea, despite EEG being mandatory. The purpose of this review is to provide an update on the evidence and controversies with regarding to the utilization of EEG for determining brain death and to serve as a cornerstone for the development of future guidelines. To determine brain death, electrocerebral inactivity (ECI) should be demonstrated on EEG at a sensitivity of 2 µV/mm using double-distance electrodes spaced 10 centimeters or more apart from each other for at least 30 minutes, with intense somatosensory or audiovisual stimuli. ECI should be also verified by checking the integrity of the system. Additional monitoring is needed if extracerebral potentials cannot be eliminated. Interpreting EEG at high sensitivities, which is required for the diagnosis of brain death, can pose a diagnostic challenge. Furthermore, EEG is affected by physiologic variables and drugs. However, no consensus exists as to the minimal requirements for blood pressure, oxygen saturation, and body temperature during the EEG recording itself, the minimal time for observation after the brain injury or rewarming from hypothermia, and how to determine brain death when the findings of ECI is equivocal. Therefore, there is a strong need to establish detailed guidelines for performing EEG to determine brain death.

Keyword

Electroencephalography; Brain death; Electrocerebral inactivity

MeSH Terms

Blood Pressure
Body Temperature
Brain Death*
Brain Injuries
Brain*
Consensus
Diagnosis*
Electrodes
Electroencephalography*
Hypothermia
Korea
Oxygen
Rewarming
Oxygen

Figure

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  Fig. 1. An example of a dummy patient with a three-lead device (Grass Technologies, West Warwick, RI, USA). This can be used to measure machine noise and external interference which enters to the recording system.

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  Fig. 2. EEG of a 70-year-old comatose male recorded 3 days after cardiopulmonary arrest. (A) The EEG appeared flat at sensitivity 7 μV/mm without any reactivity to painful stimuli. (B) Low-voltage, mixed-frequency activity was seen at sensitivity 2 μV/mm in the same epoch, which could not be eliminated. The patient never regained consciousness, spontaneous respiration, or brainstem reflexes after the cardiopulmonary arrest. A repeat EEG performed 12 days after the arrest showed the same pattern. EEG, electroencephalography.

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